International Journal of Fisheries and Aquatic Studies 2015; 3(1): 75-80 ISSN: 2347-5129 (ICV-Poland) Impact Value: 5.62 Age, growth and mortality of Streaked Gurnard (GIF) Impact Factor: 0.352 IJFAS 2015; 3(1): 75-80 © 2015 IJFAS (Trigloporus lastoviza, Bonnaterre, 1788) in the Egyptian www.fisheriesjournal.com Mediterranean waters off Alexandria Received: 11-06-2015 Accepted: 13-07-2015 Sabry S El-Serafy, Fahmy I El-Gammal, Sahar F Mehanna, Nasr-Allah H Sabry S El-Serafy Zoology Department, Faculty of Abdel- Hameid, Elsayed FE Farrag Science, Benha University. Abstract Fahmy I El-Gammal Age, growth and mortality of Streaked Gurnard Trigloporus lastoviza from the Egyptian Mediterranean Fisheries Department, National waters off Alexandria were investigated between the period from July 2009 and August 2010. The Institute of Oceanography and observed maximum age was 4 years for both sexes based on otolith readings. The length-weight Fisheries. relationship was estimated as W=0.0088L3.0694 (r=0.9854); W=0.0085L3.0836 (r=0.9803) and W=0.0106L3.0058 (r=0.9853) for males, females and combined sexes respectively. The von Bertalanffy Sahar F Mehanna Fisheries Department, National growth equations for length were: Lt=27.17 (1-e-0.3466 (t+1.01), Lt = 27.0 (1 - e -0.3703 (t + 0.93) and Institute of Oceanography and Lt = 26.92 (1 - e -0.3699 (t + 0.92) for males, females and combined sexes respectively. The growth Fisheries. performance index value (Φ) was calculated as 2.41, 2.43 and 2.43 for males, females and combined sexes respectively. The back calculated data indicated that the growth in length of T. lastoviza was Nasr-Allah H Abdel-Hameid highest at the end of the first year of life, followed by a gradual continuous decrease throughout the fish Zoology Department, Faculty of life. Total, natural and fishing mortalities were estimated for combined sexes as 1.51, 0.43 and 1.08 year-1 Science, Benha University. respectively. The results indicate that population is overexploited (E = 0.72) and suffering from high fishing pressure. Elsayed FE Farrag Fisheries Department, National Keywords: Gurnard, T. lastoviza, Alexandria, Growth, Mortality. Institute of Oceanography and Fisheries. 1. Introduction The Streaked Gurnard (Trigloporus lastoviza) is a demersal marine fish, distributed in the Mediterranean Sea and the Eastern Atlantic from England to Canary and Azores Island Akalin and Ilhan [3]. The ecology of gurnards was investigated by Papaconstantinou [29] along the [40] [11] Greek Seas, Tsimenidis et al. along the Cretean shelf (Greece), Colloca et al., in the Central Mediterranean Sea. The growth and reproduction were investigated in different localities; Baron [4, 5] in France, Faltas and Abdallah [16] in Egypt, Abdallah and Faltas [2] in Egypt, Uçkun [41] in North Aegean Sea, Olim and Borges [28] in Portugal, Sangun et al. [36] in [8] [3] Turkey, Boudaya et al. in Tunisia, Akalin and Ilhan in Izmir Bay. The aim of this study is to provide some information on age, growth and mortality of T. lastoviza in the Egyptian Mediterranean waters off Alexandria. 2. Materials and Methods Streaked gurnard specimens were collected from eastern harbor of Alexandria, Egypt by bottom trawl during the period from July 2009 to August 2010. After collection, samples were freshly examined in the laboratory and the following data were recorded for each specimen: date of capture, total length to nearst 0.1cm, total weight nearest to 0.1g, sex and stage of maturity also taken. To study age, fishes were dissected, otolith were carefully removed, cleaned, dried and examined under the binocular microscope at magnification of x25 after being immersed in glycerol. The age estimates were obtained by reading each otolith at least twice, if the readings did not coincide, the otolith was rejected. The total length otolith radius relationship was derived by plotting the total otolith radius and the total fish length. The intercept value of the regression equation was used to back-calculated Correspondence fish length at the end of each year of life according to the equation by Lee, 1920 [22]: Ln = (Lt – Elsayed FE Farrag Fisheries Department, National a) Sn/ S + a where Ln is the length at the end of n years (cm), Lt is the total length at capture Institute of Oceanography and (cm), Sn is the otolith radius to the nth annulus, S is the total otolith radius and (a) is the Fisheries. intercept with Y-axis from the relationship of length and radius. Growth was expressed in ~ 75 ~ International Journal of Fisheries and Aquatic Studies terms of the von Bertalanffy [6] equation; Lt=L∞ (1-e-k (t-to)) Table 2: Back-calculated lengths at the different years of life of T. where Lt is the fish length at age t; L∞ represent the lastoviza (females) from the Egyptian Mediterranean water, off Alexandria. asymptotic length; k is a relative growth coefficient and to theoretical age when fish length is zero. Growth parameter Age Observed Back calculated length (L∞ and K) were estimated using the a and b constants of the (year) No. length (cm) I II III IV linear relationship between Lt and L t+1 after Ford [17]-Walford I 113 15.01 14.06 [43] formula, L = L (1-e-K)+e-K Lt Where, L = a/1-b and K t+1 ∞ ∞ II 223 18.44 13.84 17.96 = -Ln (b). The initial condition parameter (to) was calculated III 108 21.08 13.66 17.82 20.84 by applying the inverse von Bertalanffy growth equation: T = o IV 10 22.93 13.52 17.75 20.62 22.64 t+ [(1/k) (Ln (L∞ - Lt)/L∞. The length-weight relationship was described by the equation; Average calculated length 13.77 17.84 20.73 22.64 W=aLb where W is the total weight (g), L is the total length Increment 13.77 4.07 2.89 1.91 (cm), a and b are the regression constants. Le Cren [21]. The % of increment 60.82 17.99 12.75 8.44 growth type was identified by Students t-test which was applied to determine the significance of differences between 3.2. Length-Weight relationship the isometric growth (b=3) and allometric growth (b#3) The total length measurements of male specimens ranged from according to the equation ts= (b-3)/Sb, where Sb is the 12 to 23cm, while the total weight measurements varied from standard error of the slope. Morey et al. [26]. 19.3 to 134.9gm. In case of females the total length and total Growth performance index (ΦL=logk+2 log L∞) were weight measurements ranged from 11 to 24cm and from 14.2 estimated by Moreau et al. [25], where k is a growth coefficient to 154.2gm respectively. The length-weight relationship [3] and L∞ is a maximum length. Total mortality rate (Z) was parameters were estimated as in Table . According to the estimated by two methods, the first is linearized catch curve student t-test, isometric growths were observed for both male Ricker [35] and the second from length-converted catch curve and female. Also for all fish, weight increased isometrically Pauly [32]. Natural mortality coefficient (M) was calculated with length. from different methods; Djabalia et al. [12], Ursin [42] and Taylor [38]. The Fishing mortality coefficient (F) and the Table 3: Length-weight relationship parameters of T. lastoviza from the Egyptian Mediterranean water off Alexandria. exploitation ratio (E) were calculated by the equation F=Z-M and E=F/Z Pauly [31] Sex N a b r t-test male 397 0.0088 3.0694 0.9854 0.5891 a 3. Results females 490 0.0085 3.0836 0.9803 0.8236 b 3.1. Age determination and growth in length All 910 0.0106 3.0058 0.9853 0.0064 The relation between the total body length and the otolith a(t-test, t<t 0.05, t=1.66), b(t-test, t<t 0.05, t=1.65) radius of T. lastoviza was establishing for the reliability of otolith for age determination. The age estimates were obtained 3.3. Back-calculated weight by reading 388 male and 454 females ranging from 11.3 to The estimation of growth in weight for each year of life for 24.4cm in total length. The constants a and b were calculated T.lastoviza was obtained by applying the calculated total using the least square method, and the relationship can be length to the length -weight equation as seen in Table (4 and expressed by the following equations: L = -1.972 + 0.447 x 5). The mean weight for each age group of males was and L = -1.505 + 0.435x for males and females respectively. estimated to be 26.80, 58.34, 92.66 and 122.39 g. during the The back-calculated lengths for males and females of T. 1st, 2nd, 3rd and 4th years of life respectively, while for lastoviza at the end of the different years of life are given in females the mean calculated weights at the end of each year of tables (1 and 2). Thus, it’s clear that, the mean calculated life were 27.65, 61.45, 97.57 and 128.03 gm. during the 1st, length at the end of each year of life for males were 13.63, 2nd, 3rd and 4th years of life respectively. The results 17.57, 20.44 and 22.38 cm for 1st, 2nd, 3rd and 4th year of life indicated that, the highest increment in weight takes place at respectively, while the back-calculated lengths at the end of the end of the third year of life for both males and females each year of life of females were 13.77, 17.84, 20.73 and 22.64 92.66g (34.32%) and 36.12gm (28.22) respectively, while the cm for1st, 2nd, 3rd and 4th years of life respectively.